PUBLIC AND PRIVATE FOREST DISTURBANCE REGIMES IN THE SOUTHERN APPALACHIANS

The choice to harvest timber depends on, among other things, the accessibility and location of the forest. This paper examines observed harvest choices derived from satellite imagery and tests for relationships between harvest probability and location, quality, and ownership attributes of the site. Results indicate that the overall probability of harvesting for public lands is significantly lower than for private lands. Substantially different disturbance patterns relative to location attributes are also established for these groups. Results suggest a way to include spatially explicit information regarding private land management in public land management plans. An example demonstrates how alternative uses of public lands might be considered in the broader context of a multiple ownership landscape.     

THE ECONOMICS OF TIMBER SUPPLY: AN ANALYTICAL SYNTHESIS OF MODELING APPROACHES

The joint supply of timber and other services from forest environments plays a central role in most forest land debates. This paper defines a general conceptual model of timber supply that provides the context for discussing both individual harvest choice and aggregate supply models. While the structure and breadth of these models has developed considerably over the last twenty years, unresolved issues remain. Supply formulations that account for the quality and vintage distribution of forest capital will be necessary for improving medium- and long-run forecasts. This will be especially important for examining the potential impacts of structural changes in forest production and timber markets. In addition, consistent aggregation of individual owners to total supply will be required to address changing forest land ownership patterns.     

Perturbation and Asymptotic Solutions for Problems in the Theory of Urban Land Rent

Simple but accurate approximate solutions for R. M. Solow's theory of urban land rent with congest cost of transportation are obtained by perturbation and asymptotic methods. Only the case of an absentee landlord is discussed though the techniques used can be modified in a straightforward manner to handle the more interesting (and mathematically more complicated) case of municipal ownership. Solow's model is also extended to have expenditures for housing and space as separate items in the budget equation. This extension eliminates the ambiguity in the value for the fraction of income after travel cost spent on ground rent, without affecting the structure of the mathematical problems associated with Solow's original theory.     

Uncovering Student Ownership in Science Learning: The Making of a Student Created Mini‐Documentary

An important challenge in urban science education is finding ways to engage all students in the learning of science. However, research in this area has consistenly shown that around middle school student engagement in science wanes. Using critical ethnographic methods this study reveals how students cultivate a sense of ownership in an informal science video project. Student ownership of what they they learn plays an important role in how they engage in the learning environment. In this study ownership is characterized by five themes, and the notion of student ownership science is challenged as an outcome. Ownership is defined as a complex, multifaceted process that captures the relationships that students build between themselves, as youth and as learners, with science as the subject they aspire to participate in and with the context in which that participation takes place.     

决策层背景多样性何以影响企业技术创新投资导向？——股权结构的调节效应检验

本文以深圳证券交易所2013~2017年创业板313家上市企业为样本,实证分析了决策层背景多样性对企业技术创新投资导向的影响以及股权结构(股权集中度和股权制衡度)的调节效应。研究表明:决策层背景多样性的三个分维度(决策层受教育程度、行业经验和任职经历的技术性背景)均对企业技术创新投资导向有显著正影响;股权集中度对决策层行业经验和任职经历的技术性背景均有显著负影响;股权集中度在决策层背景多样性与企业技术创新投资导向之间有负向调节效应;股权制衡度在决策层背景多样性与企业技术创新投资导向之间有正向调节效应。研究结论对于企业在股权结构优化、决策层建设以及技术创新投资导向的设计等方面具有积极的借鉴意义和启示。     

Ethnic Preferences and Residential Segregation: A Commentary on Outcomes from Agent-Based Modeling

Mark Fossett's new research, published here in the Journal of Mathematical Sociology, is arguably the most important advance in studies of residential segregation in the past decade. While this study of the role of preferences in creating the patterns of residential separation does not answer all the questions about how preferences create separation in the residential mosaic, it provides a major extension of Schelling's seminal work of three decades ago. The paper shows clearly that preferences do matter and that the set of simulations leave little doubt that residential preferences and their underlying social dynamics have the capacity to generate high levels of ethnic segregation. The agent-based modeling technique, on which the results are based, is a major advance on previouswork using agent-based modeling and will set the standard for further studies of the underlying processes that create residential separation in U.S. cities.     

我国居民储蓄对收入的敏感性分析

我国的居民储蓄始终高居不下,国内市场疲软,有效需求不足,这是制约整个国民经济可持续发展的一个重要症结。本文采用实证研究和理论分析相结合的方法,通过建立回归模型,进行协整分析,发现正是由于储蓄对收入强敏感性的存在,在很大程度上引发了居民的高储蓄倾向,进而探讨了其内在的原因。     

中国城镇居民生活用能影响因素定量研究

利用面板数据对中国城镇居民生活用能影响因素进行了实证分析.结果表明,能源消费总量对人均可支配收入的弹性最大,人口对城镇居民用能具有广义的规模效应,居民用能对能源价格很敏感.此外,夏季与冬季的温差每上升一摄氏度,城镇居民生活用能总量会上升3%.如果一个地区有集体供暖,其城镇居民部门能源消费总量会比没有集体供暖时减少19%.     

湖南省企业生命周期测度及其影响因素分析

本文运用生命表方法对湖南省1980年-2007年期间新成立企业的生存状况进行了测度和分析,通过考察企业生存时间的分位数、在指定时间的平均剩余寿命和在指定时间内的平均存活时间等指标,对不同城、行业、资本规模、所有制类型和成立时间的企业进行了比较研究。结果表明,不同城市、行业、资本规模、所有制类型和成立时间的企业生存时间存在较大差异,我国企业生存状况不仅受到西方传统产业组织理论中企业所在地域、行业和规模的影响,还受到由中国国情所决定的所有制性质和成立时间的影响。     

中国城镇化对碳排放的影响研究:基于居民消费的视角

将城镇化、居民消费和碳排放视作碳排放系统中的一个子系统进行深入研究,分析了三者之间的作用机理并提出了四个假设.运用1978-2013年的时间序列数据进行了实证研究,结果表明:城镇化和居民消费均是碳排放的Granger原因;城镇化并不直接产生碳排放,并且对居民消费与碳排放的关系不具有调节作用;城镇化通过影响居民消费而影响碳排放.针对分析结果,探讨了有序推进中国城镇化发展和生态文明建设的应对之策.     

Residential relocation dynamics: A microeconomic model based on agents’ socioeconomic change and learning

This article develops a mathematical model for residential location choice in which previous experience is considered via a dynamic learning process and each agent evaluates location decisions according to their utility. Agents’ idiosyncratic behavior is modeled, assuming a stochastic willingness to pay based on dwelling and neighborhood attributes and households’ socioeconomics. Additionally, the willingness to pay is affected by the agent’s experience of the urban context in previous periods. Numerical examples are given, and simulations are conducted using linear bid functions. Additionally, concepts of urban dynamics are used in the long-term, assuming quasi-equilibrium in the bids considering the externalities of urban configurations. The results are compared with a static outcome corresponding to the equilibrium model of land use. The comparison is performed using indices of urban segregation and both short- and long-term configurations. The studied dynamics show that static modeling does not explain all the features associated with such a configuration of the urban system (in both short and long term).     

住宅房地产顾客感知价值评估

不同的顾客对同一住宅房地产的感知价值是不同的,购房决策主要取决于对住宅房地产的顾客感知价值.提出了住宅房地产顾客感知价值评估的质量功能配置逆过程法,在已知住宅房地产工程特性的条件下,确定顾客需求值.利用该方法,给出了评估住宅房地产的顾客感知价值的过程和数学模型,案例研究表明,方法能有效评估住宅房地产的顾客感知价值,帮助购房者选择住宅房地产项目.     

企业人力资本所有者与所有权安排的博弈分析

我们利用博弈论的基本思想和基本方法，从人力资本所有与非人力资本所有以及人力资本所有之间博弈关系的角度，构建企业人力资本所有与所有权安排的博弈模型，从博弈的视角对企业人力资本所有与所有权安排进行分析，探究企业人力资本所有与所有权安排中参与人之间的合约关系，给出一个关于企业人力资本所有分享所有权的一般性解释。     

Ownership-specified network DEA models

To our knowledge, all network DEA models proposed in the literature so far either implicitly or explicitly assume that all entities comprised of a network (system) are owned by a single owner, i.e., a centralized system. As a result, those models are not applicable to performance evaluation for a wide variety of distributed and hybrid systems in practice. Therefore, this study aims to show the importance of taking into account the ownership structure of networks (systems) in constructing effective network DEA models, and accordingly develops three ownership-specified (centralized, distributed and hybrid) network DEA models in terms of both input- and output-orientation. A numerical example is used to validate the critical importance of the ownership with entities and thus networks in both network DEA methodologies and applications.     

“Optimization of aircraft maintenance/support infrastructure using genetic algorithms—level of repair analysis”

Level of repair analysis (LORA) is an approach used during the design stage of complex equipment for analysis of the cost effectiveness of competing maintenance strategies. LORA is carried as a part of the life cycle cost and cost of ownership analysis and plays a significant role in minimizing the life cycle cost and cost of ownership of the capital equipment. Since many purchasing decisions of complex equipment are based on cost of ownership, it has become essential to carry out LORA to compete in the market. In this paper, we develop a mathematical model for LORA and propose a solution methodology based on genetic algorithms. The concept is illustrated using a hypothetical aircraft engine.     

Historical and future dynamics of land use land cover and its drivers in Ajora-Woybo watershed,Omo-Gibe basin,Ethiopia

Land use land cover (LULC) dynamics have long been recognized as a significant driver of natural resource change. As a result, understanding the spatial and temporal variation of LULC in the watershed is essential for effective natural resource management and long-term development. This study attempts to analyze the dynamics and change drivers from 1990 to 2020 and predict the situation for 2035 and 2050 in the Ajora-Woybo watershed. ArcGIS 10.3 and ERDAS 2015 were used to analyze quantitative data from Landsat imagery. For supervised image classification, a Maximum-Likelihood classification algorithm was used. To identify driver variables, focus groups and key informants' interviews were done. TerrSet 18.31 software was used to predict LULC utilizing the Multi-Layer Perceptron Neural Network and Cellular Automata-Markov Chain models incorporated in Land Change Modeler. Six LULC classes were discovered: cultivated land, built-up, shrub land, forest land, bare land, and water body. Cultivated land, built-up area, and bare land have increased at the expense of shrub land and forest land over the last three decades. Trends in water bodies show both decreasing and increasing trends. According to the predicted outcomes, cultivated land, built-up and bare land has increased, while shrub land and forest land have declined. Finally, agricultural expansion, population growth, wood extraction, resettlement, urbanization, and lack of environmental consideration were identified as the major drivers of LULC change. The study demonstrated that there have been significant changes in the watershed LULC. As a result, reversing the predicted conditions is critical to ensuring the watershed long-term viability.     

基于多层博弈的智能电网住宅电力实时需求响应机制

通过建立多层博弈模型刻画智能电网系统中电力公司、家庭电力管理中心和家庭内各个电器设备间的电力实时需求响应过程。在此模型中,每个时段电力公司将电价通知各个家庭,每个家庭的电力管理中心接收到实时电价信息后为家庭内各个电器设备分配虚拟电价,各个设备则确定各自最优用电量并将其反馈给家庭电力管理中心,由其确定该家庭总用电量并发送至电力公司,电力公司再计算得到最优电价。证明了所建多层博弈模型的均衡存在唯一性,并得到均衡解。仿真结果验证了模型的有效性,并给出其实际应用价值。     

Improving the efficiency of the purchasing process using total cost of ownership information: The case of heating electrodes at Cockerill Sambre S.A.

Improving the efficiency of the purchasing process provides important opportunities to increase a firm's profitability. In this paper we introduce a mathematical programming model that uses total cost of ownership information to simultaneously select suppliers and determine order quantities over a multi-period time horizon. The total cost of ownership quantifies all costs associated with the purchasing process and is based on the activities and cost drivers determined by an activity based costing system. Our approach is motivated by the purchasing problem of heating electrodes at Cockerill Sambre, a Belgian multinational steel producer. In this case quality issues account for more than 70% of the total cost of ownership making the quality of a supplier a critical success factor in the supplier selection process.     

国有企业人力资本与所有权安排的实证分析

本首先对中国国有企业人力资本与所有权安排制度作一简要考察，然后对中国国有企业人力资本与所有权安排问题进行实证分析，在此基础上进一步对国有企业人力资本与所有权安排的制度进行分析。     

土地市场波动与房地产价格的关系分析:基于VAR模型的实证研究

随着中国经济增长、城市化的发展,房价不断攀升,居民面临巨大的购房压力,而政府也开始对房地产市场进行调控,在房价构成因素中,土地成本占有很大比重,因此土地价格,土地供应面积与房地产价格之间的关系研究对促进房地产市场的合理发展有十分重要的意义.以2002年到2011年我国土地供应面积,土地购置价格和房地产价格的月度数据为样本,对土地供应面积,土地购置价格与房地产价格进行协整检验后,构建VAR模型进行格兰杰因果检验后发现土地供应价格,面积和房地产价格互为因果;对城市土地购置价格和房地产价格进行脉冲响应分析和方差分解后发现房地产价格和土地价格之间的存在相互影响,且在短期内都受土地供应面积的影响但程度不高.